vmm_memory.c

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/*****************************************************************************************
 Copyright (c) 2002-2004 The UbixOS Project
 All rights reserved.

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 conditions, the following disclaimer and the list of authors.  Redistributions in binary
 form must reproduce the above copyright notice, this list of conditions, the following
 disclaimer and the list of authors in the documentation and/or other materials provided
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 EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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 OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 $Id$

*****************************************************************************************/

#include <vmm/vmm.h>
#include <sys/io.h>
#include <ubixos/kpanic.h>
#include <lib/kprintf.h>
#include <lib/kmalloc.h>
#include <sys/kern_sysctl.h>
#include <ubixos/spinlock.h>
#include <assert.h>

static uInt32          freePages = 0;
static spinLock_t vmmSpinLock    = SPIN_LOCK_INITIALIZER;
static spinLock_t vmmCowSpinLock = SPIN_LOCK_INITIALIZER;


int             numPages = 0x0;
mMap           *vmmMemoryMap = (mMap *) 0x101000;


int vmmMemMapInit() {
  int i        = 0x0;
  int memStart = 0x0;

  /* Count System Memory */
  numPages = countMemory();

  /* Set Memory Map To Point To First Physical Page That We Will Use */
  vmmMemoryMap = (mMap *) 0x101000;

  /* Initialize Map Make All Pages Not Available */
  for (i = 0x0; i < numPages; i++) {
    vmmMemoryMap[i].cowCounter = 0x0;
    vmmMemoryMap[i].status     = memNotavail;
    vmmMemoryMap[i].pid        = vmmID;
    vmmMemoryMap[i].pageAddr   = i * 4096;
    }

  /* Calculate Start Of Free Memory */
  memStart  = (0x101000 / 0x1000);
  memStart += (((sizeof(mMap) * numPages) + (sizeof(mMap) - 1)) / 0x1000);

  /* Initialize All Free Pages To Available */
  vmmMemoryMap[(0x100000 / 0x1000)].status = memAvail;
  freePages++;
  for (i = memStart; i < numPages; i++) {
    vmmMemoryMap[i].status = memAvail;
    freePages++;
    }

  /* Print Out Amount Of Memory */
  kprintf("Real Memory:      %iKB\n", numPages * 4);
  kprintf("Available Memory: %iKB\n", freePages * 4);

  /* Return */
  return (0);
  }

int countMemory() {
  register uInt32 *mem = 0x0;
  unsigned long    memCount = -1, tempMemory = 0x0;
  unsigned short   memKb = 0;
  unsigned char    irq1State, irq2State;
  unsigned long    cr0 = 0x0;

  /*
   * Save The States Of Both IRQ 1 And 2 So We Can Turn Them Off And Restore
   * Them Later
   */
  irq1State = inportByte(0x21);
  irq2State = inportByte(0xA1);

  /* Turn Off IRQ 1 And 2 To Prevent Chances Of Faults While Examining Memory */
  outportByte(0x21, 0xFF);
  outportByte(0xA1, 0xFF);

  /* Save The State Of Register CR0 */
  asm volatile (
    "movl %%cr0, %%ebx\n"
    :               "=a" (cr0)
    :
    :               "ebx"
    );

  asm volatile ("wbinvd");
  asm volatile (
    "movl %%ebx, %%cr0\n"
    :
    :               "a" (cr0 | 0x00000001 | 0x40000000 | 0x20000000)
    :               "ebx"
    );

  while (memKb < 4096 && memCount != 0) {
    memKb++;
    if (memCount == -1)
      memCount = 0;
    memCount += 1024 * 1024;
    mem = (uInt32 *)memCount;
    tempMemory = *mem;
    *mem = 0x55AA55AA;
    asm("": : :"memory");
    if (*mem != 0x55AA55AA) {
      memCount = 0;
      }
    else {
      *mem = 0xAA55AA55;
      asm("": : :"memory");
      if (*mem != 0xAA55AA55) {
        memCount = 0;
        }
      }
    asm("": : :"memory");
    *mem = tempMemory;
    }

  asm volatile (
    "movl %%ebx, %%cr0\n"
    :
    :               "a" (cr0)
    :               "ebx"
    );

  /* Restore States For Both IRQ 1 And 2 */
  outportByte(0x21, irq1State);
  outportByte(0xA1, irq2State);

  /* Return Amount Of Memory In Pages */
  return ((memKb * 1024 * 1024) / 4096);
  }

uInt32 vmmFindFreePage(pidType pid) {
  int i = 0x0;

  /* Lets Look For A Free Page */
  if (pid < sysID)
    kpanic("Error: invalid PID %i\n",pid);

  spinLock(&vmmSpinLock);

  for (i = 0; i <= numPages; i++) {

    /*
     * If We Found A Free Page Set It To Not Available After That Set Its Own
     * And Return The Address
     */
    if ((vmmMemoryMap[i].status == memAvail) && (vmmMemoryMap[i].cowCounter == 0)) {
      vmmMemoryMap[i].status = memNotavail;
      vmmMemoryMap[i].pid = pid;
      freePages--;
      if (sysctl_enabled == TRUE) {
        systemVitals->freePages = freePages;
        }

      spinUnlock(&vmmSpinLock);
      return (vmmMemoryMap[i].pageAddr);
      }
    }

  /* If No Free Memory Is Found Return NULL */
  kpanic("Out Of Memory!!!!");
  return (0x0);
  }


int freePage(uInt32 pageAddr) {
  int pageIndex = 0x0;
  assert((pageAddr & 0xFFF) == 0x0);
  spinLock(&vmmSpinLock);

  /* Find The Page Index To The Memory Map */
  pageIndex = (pageAddr / 4096);

  /* Check If Page COW Is Greater Then 0 If It Is Dec It If Not Free It */
  if (vmmMemoryMap[pageIndex].cowCounter == 0) {
    /* Set Page As Avail So It Can Be Used Again */
    vmmMemoryMap[pageIndex].status = memAvail;
    vmmMemoryMap[pageIndex].cowCounter = 0x0;
    vmmMemoryMap[pageIndex].pid = -2;
    freePages++;
    systemVitals->freePages = freePages;
    }
  else {
    /* Adjust The COW Counter */
    adjustCowCounter(((uInt32) vmmMemoryMap[pageIndex].pageAddr), -1);
    }
  spinUnlock(&vmmSpinLock);
  /* Return */
  return (0);
  }

int adjustCowCounter(uInt32 baseAddr, int adjustment) {
  int vmmMemoryMapIndex = (baseAddr / 4096);
  assert((baseAddr & 0xFFF) == 0x0);
  spinLock(&vmmCowSpinLock);
  /* Adjust COW Counter */
  vmmMemoryMap[vmmMemoryMapIndex].cowCounter += adjustment;

  if (vmmMemoryMap[vmmMemoryMapIndex].cowCounter == 0) {
    vmmMemoryMap[vmmMemoryMapIndex].cowCounter = 0x0;
    vmmMemoryMap[vmmMemoryMapIndex].pid = vmmID;
    vmmMemoryMap[vmmMemoryMapIndex].status = memAvail;
    freePages++;
    systemVitals->freePages = freePages;
    }
  spinUnlock(&vmmCowSpinLock);
  /* Return */
  return (0);
  }

void vmmFreeProcessPages(pidType pid) {
  int i=0,x=0;
  uInt32 *tmpPageTable = 0x0;
  uInt32 *tmpPageDir   = (uInt32 *)parentPageDirAddr;
  spinLock(&vmmSpinLock);
  /* Check Page Directory For An Avail Page Table */
  for (i=0;i<=0x300;i++) {
    if (tmpPageDir[i] != 0) {
      /* Set Up Page Table Pointer */
      tmpPageTable = (uInt32 *)(tablesBaseAddress + (i * 0x1000));
      /* Check The Page Table For COW Pages */
      for (x=0;x<pageEntries;x++) {
        /* If The Page Is COW Adjust COW Counter */
        if (((uInt32)tmpPageTable[x] & PAGE_COW) == PAGE_COW) {
          adjustCowCounter(((uInt32)tmpPageTable[x] & 0xFFFFF000),-1);
          }
        }
      }
    }

  /* Loop Through Pages To Find Pages Owned By Process */
  for (i=0;i<numPages;i++) {
    if (vmmMemoryMap[i].pid == pid) {
      /* Check To See If The cowCounter Is Zero If So We Can Ree It */
      if (vmmMemoryMap[i].cowCounter == 0) {
        vmmMemoryMap[i].status = memAvail;
        vmmMemoryMap[i].cowCounter = 0x0;
        vmmMemoryMap[i].pid = vmmID;
        freePages++;
        systemVitals->freePages = freePages;
        }
      }
    }
  /* Return */
  spinUnlock(&vmmSpinLock);
  return;
  }

/***
 END
 ***/

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